KR20050112692A - The Preparation method of monodispersed iron oxide nanoparticles from microdroplets of ferrous(Ⅱ) and ferric(Ⅲ) chloride solutions generated by piezoelectric nozzle - Google Patents

Abstract

The present invention comprises the steps of: (a) dissolving iron (II) chloride and iron (III) chloride in water and sonicating uniformly; (b) spraying the dissolved solution of step a through a small piezoelectric element nozzle having a diameter of 10 to 100 microns so as to have a predetermined size, and dropping the droplets into an alkaline solution serving as a reaction catalyst; (c) stirring and reacting the alkaline solution of step b by sonication to form iron oxide magnetite in the droplets; And (d) oxidizing the iron oxide magnetite formed in step c to form iron oxide maghemite.

Description

The preparation method of monodispersed iron oxide nanoparticles from microdroplets of ferrous (II) and ferric (III) in a microdroplet reactor of iron (II) chloride and (III) chloride by piezoelectric element nozzles chloride solutions generated by piezoelectric nozzle}

The present invention relates to a method for producing mono-dispersed iron oxide nanoparticles, more specifically, may have a narrow particle distribution of less than 10nm, iron oxide nanoparticles that can be uniformly dispersed even after the production of iron oxide nanoparticles without entanglement between particles It relates to a manufacturing method of.

In general, iron oxide is produced in a variety of forms in nature and has been mainly used in the steel and steel industry, and natural or synthetic iron oxide has been used in a variety of non-metal industry. In addition, by using the chemical electromagnetic properties of iron oxide synthesized in the form of particles are used in a wide range of applications, such as electronic materials, medical, bio-industry. Iron oxide is a compound of iron and oxygen, and iron (II) oxide, iron (III) oxide and triiron tetraoxide are largely included. Iron (II) oxide (ferrous oxide, formula FeO) is also called iron monoxide or iron dioxide, and iron oxide (III) is hydrogen It is produced by reducing it to or by blocking the air and heating iron oxalate, but it is difficult to obtain pure one. When heated in air, it becomes iron (III) oxide, which is made at low temperature, is rich in reactivity and shows strong magnetism. It is reduced by hydrogen to produce iron. In addition, iron (III) oxide (ferric oxide, the formula Fe ₂ O ₃ ) is also called ferric trioxide or iron trioxide, depending on the crystal structure hematite (hereinafter hematite, hematite, a-Fe ₂ O ₃ ) and maghemite (hereinafter referred to as Maghemite, maghemite, r-Fe ₂ O ₃ ) is a reddish brown powder, which is fairly stable against sunlight, air, moisture, heat, etc. Iron (III) oxide is produced by heating iron in air. In the past, it was made by baking iron sulfate, but recently it is made from iron sulfate or iron chloride produced from the waste liquid of the steel industry or plating industry as a raw material. According to the manufacturing method, the color may be yellow, brown, purple, or black, but the color may be different from the particle size, the type of the mixed matter, and the completeness of the crystal lattice. It is industrially used as a red pigment called Bengala, and used as an abrasive for glass, precious metals and diamonds, and a high purity is used as a semiconductor, and also as a raw material for magnets and magnetic tapes. And ferric tetraoxide is called magnetite (hereinafter magnetite, magnetite, Fe ₃ O ₄ ), a black heavy powder, naturally produced as magnetite.

In addition, iron oxides are manufactured in nano and micro sized particle forms in various ways for application to electronic materials and bio industry. Currently, nano and micro sized iron oxide particles are manufactured using iron (II) chloride (FeCl ₂ · 4H ₂ O). And iron (III) chloride (FeCl ₃ · 6H ₂ O) are reacted by high temperature chemical solution method, and ion pentacarbonyl (hereinafter, pentacarbonyl, iron pentacarbonyl, Fe (CO) ₅ ) is reacted by high temperature chemical solution method. It is synthesize | combined by the ultrasonic wave method, the chemical precipitation method, etc. However, nano and micro-sized iron oxide particles produced by such a process method has a wide distribution in the size of the particles, and it is not easy to manufacture the particles to a size of 10 nm (hereinafter referred to as nano) or less, and the iron oxide particles at the time of manufacture Due to the entanglement of the liver, it has a problem that it is not easy to disperse in the dispersion medium. This is because it is difficult to control the size of the particles and control the reaction phase in the process of producing the particles.

On the other hand, as similar to the present invention, there are Korean Patent Registration No. 10-0014271-0000, Korean Patent Publication No. 1997-0066732, and Korean Patent Publication No. 2002-0063116, which are based on the process method of preparing the iron oxide particles and the size of the iron oxide particles after production There is a different content from the technical configuration of the present invention, there is a US patent application US496972 but this is different from the technical configuration of the present invention in the manufacturing process method and the type of particles, 2004-0011099 relates to an inkjet printer using an inkjet head, a multifunction device including an inkjet printer, and the like, and more particularly, to a method and a device for printing a document according to the state of an inkjet nozzle. The contents are different from the technical configuration mainly controlling the size of the post iron oxide particles.

The present invention has been made to solve the problems of the prior art,

An object of the present invention is to prepare a nano-sized iron oxide particles dissolved iron (II) chloride and iron (III) in water by ultrasonic stirring at room temperature, and then mixed, and then dissolved iron (II) chloride and iron (III) chloride dissolved The liquid is dropped into the alkaline solution in the form of droplets through a piezoelectric element nozzle and stirred by ultrasonic wave to have a narrow particle distribution of 10 nm or less, and even after the production of the iron oxide nanoparticles, there is no entanglement between particles, resulting in uniform dispersion. The present invention provides a method for producing iron oxide nanoparticles.

The present invention comprises the steps of: (a) dissolving iron (II) chloride and iron (III) chloride in water and sonicating uniformly; (b) spraying the dissolved solution of step a through a small piezoelectric element nozzle having a diameter of 10 to 100 microns so as to have a predetermined size, and dropping the droplets into an alkaline solution serving as a reaction catalyst; (c) stirring and reacting the alkaline solution of step b by sonication to form iron oxide magnetite in the droplets; And (d) oxidizing the iron oxide magnetite formed in step c to form iron oxide maghemite.

 The microdroplet reactor used in the present invention is a microsized droplet as described above, and uniformly by precipitating nanoparticles in the microdroplets by reacting iron (II) chloride with iron (III) chloride by applying appropriate energy with ultrasonic waves. It provides a method for obtaining nanoparticles. According to the method of the present invention, it is possible to uniformly adjust the size of the particles, thereby obtaining a uniform particle size distribution, high particle production efficiency and good dispersibility of the produced particles, easy to mass production, The benefits of being environmentally friendly can also be obtained.

The molar ratio of iron (II) chloride and iron (III) chloride in step a is not particularly limited, but preferably a ratio of 1 mol (mol) of iron (II) chloride and 2 mol (mol) of iron (III) chloride (iron chloride (II) ) / Iron (III) = 0.5). If the molar ratio is increased or decreased, the precipitate produced in the chemical reaction may affect the reaction.

When the iron (II) chloride and iron (III) chloride are mixed in water, the total iron chloride content is preferably 10 to 20 parts by weight.

The sonication in step a above does not require any special limitation as long as it is to uniformly mix iron (II) chloride and iron (III) chloride in water, but preferably 20 to 20 using a known ultrasonic treatment apparatus. Ultrasound of 50 kHz, 50-100 W can be used. The sonication process may be performed at 15 to 60 ° C. for 20 to 40 minutes.

In step b, a piezoelectric element nozzle (hereinafter referred to as a piezoelectric nozzle) is used to droplet the dissolved solution in which the iron (II) chloride and the iron (III) chloride are uniformly mixed. The droplet manufacturing apparatus including the fine piezoelectric nozzle used in the present invention is a droplet form through a small nozzle having a micro-sized diameter while vibrating the solution through a piezoelectric transducer (hereinafter referred to as a piezoelectric transducer). It is configured to be discharged to. Droplets sprayed through the nozzle may be formed as micro droplets having a uniform size by adjusting the nozzle diameter, frequency, and solution composition as fine droplets having a diameter of a micro size.

In more detail, when a solution is injected through a microelectron nozzle, a thin cylinder-like stream of water flows. At this time, when the tip of the nozzle is vibrated through a piezoelectric transducer, periodic instability caused at this time is cylindrical. The stream of water is transformed into a series of drops of uniform size. At this time, the size of the nozzle is affected by the size of the nozzle diameter, thereby obtaining particles of uniform size. In general, as the size of the nozzle diameter increases, the size of the iron oxide nanoparticles may be slightly increased.

As described above, the piezoelectric element nozzle in the present invention grinds a mixed solution of iron (II) chloride and iron (III) chloride into fine droplets, and then adjusts the size of the iron oxide nanoparticles ultimately obtained through a predetermined reaction in the droplets. It plays a central role. The diameter of the piezoelectric element nozzle is not particularly limited, but may be preferably selected from 10 to 100 μm (hereinafter, micro). If the diameter of the nozzle is less than 10 micro, it may be affected by the flow of the solution in the nozzle by air or fine foreign matter in the solution.If the diameter of the nozzle exceeds 100 micro, the solution sprayed through the nozzle is large. Dropping problems can occur.

In the droplet formation step of step b, droplet formation may be preferably performed by spraying the solution through the piezoelectric element nozzle under the condition of the frequency of the piezoelectric transducer of 15 to 25 kHz and the injection speed of 0.006 to 0.02 ml / sec. When the frequency is out of the above range, it is out of the range of periodic optimum vibration caused by the piezoelectric transducer that stimulates the nozzle tip, and thus it is not easy to convert the cylindrical body of water into a series of droplets of uniform size. If the speed is out of the above range may be a condition that is out of the optimum flow phenomenon of the sprayed solution may cause a problem that particles having a wide distribution is produced.

The alkaline solution of step b is provided as a reaction catalyst, but is not particularly limited. In order to solve the problem of having a large particle and a wide particle distribution in the ease of particle formation and particle size, the pH is preferably 12 to 14. An alkaline solution is used. Examples of such alkaline solutions are sodium hydroxide or ammonium hydroxide solutions.

Step c is a process of performing the reaction in a uniformly dispersed droplet by treating the alkaline solution with ultrasonic waves. In the droplets, a mixture of iron (II) chloride and iron (III) chloride reacts to form a black iron oxide magnetite. Such a reaction may be preferably using ultrasonic waves of 20 to 50 kHz, 50 to 100 W using a known ultrasonic treatment apparatus, and the ultrasonic treatment may be performed at 15 to 60 ° C. for 20 to 60 minutes.

The iron oxide magnetite obtained through the above process is washed and then subjected to an oxidation process by heat treatment at 100 to 300 ° C. to produce reddish brown iron oxide magnetite. Iron oxide maghemite prepared by such a process can be prepared as uniform monodisperse nanoparticles of 10 nm or less by a simple process of adjusting the size of the nozzle used.

Hereinafter, the content of the present invention will be described in more detail with reference to Examples. However, these examples are only presented to understand the content of the present invention, and the scope of the present invention should not be construed as being limited to these embodiments.

<Example 1>

At room temperature, the ratio of 1 mol (mol) of iron (II) chloride and 2 mol (mol) of iron (III) chloride (iron (II) chloride / iron (III) chloride = 0.5) was obtained by using ultrasonic (Branson Co., USA, Bransonic 1510, 20KHz, 70W), dissolved in 10ml of water and mixed.

The resulting solution was subjected to a piezoelectric transducer (Agilent, model 33120A) using a micro-piezoelectric nozzle (MicroFab Technologies Inc., USA) having a diameter of 50 microns at a frequency of 20 KHz and a spray rate of 0.01 ml / sec. The solution was dropped into M sodium hydroxide solution, and stirred for 30 minutes by ultrasonication (Branson Co., USA, Bransonic 1510, 20KHz, 70W).

The reaction solution was washed with water and heat-treated at 250 to 300 ° C. for 1 to 2 hours. The monodisperse iron oxide magnetite or maghemite nanoparticles having a narrow particle size of 3 to 5 nanometers and an average particle size of 4.3 nanometers were obtained. Was prepared.

Meanwhile, X-ray analysis (hereinafter referred to as X-ray, XRD, X-ray Diffraction, and KAIST XRD Analysis Center in Korea) was used to analyze the crystal structure of the manufactured iron oxide nanoparticles, and the results were obtained from the X-ray standard pattern document table (Powder Diffraction file, JCPOS card). No. 19-0629 (magnetite), 25-1402 (maghemite)) is shown in Table 1 below.

Table 1 Crystal Structure Analysis of the Prepared Iron Oxide Nanoparticles

bulkFe ₃ O ₄ bulkγ-Fe ₂ O ₃ Fe ₃ O ₄ r-Fe ₂ O ₃ d (A) intensity d (A) intensity d (A) intensity d (A) intensity (JCPOS19-0629) (JCPOS25-1402) (Magnetite) (Maghemite) 2.967 2.950 2.961 2.950 2.532 2.514 2.532 2.513 2.099 2.086 2.099 2.086 1.714 1.701 1.709 1.701 1.616 1.604 1.613 1.605 1.485 1.474 1.480 1.474

<Example 2>

At room temperature, a ratio of 1 mol (mol) of iron (II) chloride and 2 mol (mol) of iron (III) chloride (iron (II) chloride / iron (III) chloride = 0.5) was obtained by ultrasonic (Branson Co., USA, Bransonic 1510, 20KHz, 70W), dissolved in 5 ml of water and mixed. The solution was dropped into a 1.2 M sodium hydroxide solution at pH 13.5 through a piezoelectric element nozzle with a diameter of 20 kHz at a frequency of 20 kHz and a spray rate of 0.01 mL / sec, followed by ultrasonication (Branson Co., USA) for 30 minutes. , Bransonic 1510, 20KHz, 70W) was treated and stirred.

The reaction solution was washed with water, and heat-treated at 250 to 300 ° C. for 1 to 2 hours. The monodisperse iron oxide magnetite or maghemite nanoparticles having a narrow particle size distribution of 8 to 10 nanometers and an average particle size of 9.1 nanometers were obtained. Was prepared. Table 2

Meanwhile, the average particle size of monodisperse iron oxide nanoparticles was measured and calculated using a transmission electron microscope (TEM, model CM20, philips, USA) and the theoretical calculation method through magnetic characteristics analysis of iron oxide nanoparticles T _B = KV / 25k _B The results are shown in Table 2 below. At this time, T _B is the blocking temperature, K is the anisotropy constant, V is the volume of nanoparticles, k _B is Boltzmann's constant.

Table 2 Sizes of iron oxide nanoparticles according to the diameter of the micro electric nozzle

Nozzle Diameter Distribution unit of iron oxide nanoparticles: nm (%) Average particle size 50 micro 2.6 (4.9%) 3.2 (35.2) 3.8 (40.3) 4.4 (13.9) 5.0 (5.7) 4.3 nm 100 micro 7.8 (6.1%) 8.5 (13.0) 8.7 (23.8) 9.3 (32.8) 9.7 (16.0) 10.0 (8.3) 9.1 nm

<Example 3>

Monodisperse iron oxide nanoparticles were prepared in the same manner as in Example 1, except that 1N-ammonium hydroxide (NH ₄ OH, Ammonium hydroxide, Sigma Aldridge) was used as the alkaline solution.

According to the present invention, iron oxide nanoparticles having a narrow particle distribution of 10 nm or less can be produced. In addition, even after the production of the iron oxide nanoparticles there is no entanglement between particles it is possible to produce a uniformly dispersed iron oxide nanoparticles.

1 is a transmission electron micrograph of the monodisperse iron oxide nanoparticles according to the present invention.

Claims (7)

(a) dissolving iron (II) chloride and iron (III) chloride in water and sonicating to homogeneously; (b) spraying the dissolved solution of step a through a small piezoelectric element nozzle having a diameter of 10 to 100 microns so as to have a predetermined size, and dropping the droplets into an alkaline solution serving as a reaction catalyst; (c) stirring and reacting the alkaline solution of step b by sonication to form iron oxide magnetite in the droplets; And (d) oxidizing the iron oxide magnetite formed in step c to form iron oxide maghemite. The method according to claim 1, wherein the ultrasonic treatment in step a uses ultrasonic waves of 20 to 50 kHz and 50 to 100 W. The method according to claim 1, wherein the molar ratio of iron (II) chloride and iron (III) chloride in step a is 1: 2. The method according to claim 1, wherein in the step b, the solution is dropleted by spraying through a piezoelectric element nozzle having a diameter of 10 to 100 microns. 5. The method according to claim 1 or 4, wherein the droplet formation in the dropletization step of step b is performed by injecting a solution through the piezoelectric element nozzle under conditions of a frequency of 15 to 25 kHz and a spray rate of 0.006 to 0.02 ml / sec of the piezoelectric transducer. Forming method characterized in that The method according to claim 1, wherein the alkaline solution of step b is a solution having a pH of 12 to 14. The method according to claim 1, wherein the alkaline solution of step b is sodium hydroxide or ammonium hydroxide solution.